Legacy Client Bug(s) ?

I usually use the legacy client to play League because whenever I use the new client and enter a match, my client usually freezes during champ select. By the time the client responds, the pick/ban champion timer has run out and I get a ban timer.

That being said, whenever I start up the legacy client, I get a window saying that LoL client has stopped working and that it needs to shut down, despite the fact that the client works perfectly even when this window pops up. The only weird thing I see is that the intro that the client was playing was the Warwick rework intro, not the Blood Moon Diana one. This usually happens about maybe 75% of the time, and I have no idea what is causing the error window to pop up

Any response relating to the issue is appreciated (notice me Rito)